1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel with a low firing voltage.
2. Description of the Prior Art
The plasma display panel (PDP) has great potential in the big-size flat display market. A prior art plasma display panel requires a high firing voltage to transform an ionizable gas such as argon into a plasma. Driving the plasma display panel at high voltage not only requires expensive driving and control components, but may also damage the components thus shortening their life spans.
Please refer to FIG. 1. FIG. 1 is a sectional view of a prior art plasma display panel 10. The plasma display panel 10 comprises a first substrate 12 and a second substrate 18 positioned in parallel with each other, an ionizable gas 27 filled between the two substrates 12 and 18, a plurality of first electrodes 26, a plurality of second electrodes 28, and a plurality of third electrodes 20. The first electrodes 26 and the second electrodes 28 are alternately installed in parallel on the first substrate 12. The third electrodes 20 are installed on the second substrate 18 perpendicular to the first and second electrodes 26, 28. The plasma display panel 10 further comprises a dielectric layer 14 installed above the first substrate 12, a protective layer 16 coated above the dielectric layer 14, a plurality of fluorescent phosphorus layers 22 installed above the third electrodes 20 for generating fluorescent light, and a plurality of rib 24 installed on the third electrodes 20 for isolating two adjacent fluorescent phosphorus layers 22.
Each area between one of the third electrodes 20 and a pair of neighboring first and second electrodes 26,28 defines a display unit 30 for generating plasma from the ionizable gas 27 in the display unit and driving the plasma. When a high voltage is charged between the first and second electrodes 26, 28, the electric field between the two electrodes 26, 28 causes the electrons of the ionizable gas 27 to ionize thereby generating spatial charges. After the spatial charges are generated, the third electrode 20 interacts with the first electrode 26 or second electrode 28 to generate a plasma and determine if the generated wall charges have a sufficient density to light the plasma. The wall charge density is the critical factor in maintaining the display unit 30 in the bright (on) state or in the dark (off) state. If it is decided not to maintain the display unit 30 in the bright state, the spatial charges of the display unit 30 are quickly restored to normal ionizable gas 27 (non-ionized state). If it is decided to maintain the display unit 30 in the bright state, the first and second electrodes 26, 28 drive the plasma in the display unit 30 back and forth for continuous radiating ultraviolet rays. When ultraviolet rays are radiated to the fluorescent phosphorus layer 22, the fluorescence will gleam, and the gleamed light emitted by the display unit 30 will be seen by the user through the transparent substrate 12.
The first and second electrodes 26, 28 comprise opaque conductors 261, 281 made of CrCuCr material and transparent conductors 262, 282 made of ITO material. The CrCuCr material is highly conductive but is opaque. The ITO material is partially transparent but has higher resistance. The firing voltage of the display unit 30 is related to the distance between the ITO material 262 of the first electrode 26 and the ITO material 282 of the second electrode 28. Although the transparent conductors 262, 282 formed by ITO material will absorb part of the visible light and are associated with higher resistance, they can be used for shortening the distance between the first and second electrodes 26, 28 so as to reduce the firing voltage of the display unit 30.
Although the first and second electrodes 26, 28 formed by the CrCuCr and ITO materials reduce the firing voltage of the display unit 30, the absorption of visible light by the transparent conductors 262, 282 formed by the ITO material will decrease the brightness of the display, and the resistance of the ITO material will result in a loss of energy.